Magnetic resonance imaging (MRI) of the breast has emerged as an important new diagnostic tool for the detection of tumors. Pre-surgical MRI can help to reduce the number of biopsies that need to be taken by distinguishing benign from malignant tumors. Likewise, MRI techniques provide opportunities for staging malignant tumors that can play an important role in breast preserving surgery. More recently, MRI has been employed to achieve MR-guided subcutaneous core biopsies, allowing for coordination of minimally invasive surgery. Introducing contrast agents such as gadolinium-diethylene triamine-pentaacetic acid (Gd-DTPA) during MR imaging provides sensitivity approaching 100%. An added benefit of MRI is the ability to accomplish sentinel node identification with simultaneous fat suppression. Following surgery for tumor excision, MRI is the modality of choice for the detection of residual disease. MRI is also the modality of choice for evaluating the integrity of breast implants.
The components involved in magnetic resonance imaging (MRI) include a primary magnet, computer controlled shim coils to produce field homogeneity, gradient coils to generate linear fields, radio frequencies (rf) for transmitting rfpulses and also for receiving MR imaging signals unless separate receiving coils are integrated, and advanced specialized software for data acquisition, analysis and pulse sequence. MR imaging involves exposing nuclei to a strong magnetic field and then excitation by rf resonant energy.
Despite the sensitivity MR imaging provides over more traditional imaging modalities, such as mammography or ultrasound, there are several technological hurdles. While providing exceptional sensitivity, it displays variable specificity that represents a major limitation. Given this varying specificity, when tumors are detected by MR imaging that cannot be identified with more traditional imaging modalities, patient management decisions are difficult.
To aid enhanced MR imaging of the breast, MRI equipment manufacturers have developed and marketed breast coils. Breast coils are usually whole-volume solenoids used for transmission and receiving. Resonators are applied over the breast, usually in pairs, to allow for simultaneous imaging of both breasts. The quality of the MR image produced can be enhanced by the optimal use of an independent coil, called a surface coil, placed close to the area being imaged in order to improve the strength of any received signal. Many of the breast coils are system and/or manufacturer specific.
In using the above-mentioned breast coils, the female patient lies face down and head first. The breasts must be positioned in the center of the coils. The salient feature common to all of these breast coils is the need to adequately position the breasts, which are hanging pendulantly. Another common feature of the breast coils is the need for some form of compression to immobilize the breasts within the coil to properly position breasts for imaging and adapt the apertures for variation in individual breast size. These “one size fits all” breast coils rely on manual compression of the breast tissue by an MR imaging technician.
The need to disrobe and have one's breasts manipulated, positioned and compressed by a stranger can be an uncomfortable and intimidating experience for a female patient. It is also a major reason why women avoid routine breast screening. The imaging device of the present invention can be applied by the patient herself in the privacy of a dressing room unlike the MR imaging devices for the breast in use today where the breasts must be positioned by a technician. Since almost all women know their appropriate brassiere size and also know how to position it on their anatomy, an imaging device which adopts a brassiere or corset design represents an easy to use and comfortable configuration. Just as importantly, it provides a sense of independence and dignity in an otherwise intimidating process.